1. Field of the Invention
This invention relates to prosthetics. More particularly, it relates to a non-anatomical artificial finger or fingertip that does not require complex control systems.
2. Description of the Prior Art
Most upper extremity amputations are the result of abnormal development, trauma, or medical treatment. Amputations of the hand result in chronic disability. Conventional designs of artificial hands do not perform well at grasping different shapes and sizes of objects. Depending on the design, conventional artificial hands may need complex control systems to coordinate the articulations.
Thus there is a need for an alternate mechanism that improves upon hooks and other forms of non-anatomical prosthetic hands. Current designs of myoelectric devices will also benefit from mechanical adaptations to make them more versatile and functional.
U.S. patent application No. 0234564, entitled Enhanced-Functionality Prosthetic Limb, filed Oct. 20, 2005 by Fink et al, discloses an enhanced functionality prosthetic hand or gripping device and fore arm which is manually or motor powered, intended primarily for pediatric use. The inventive structure is attached to the residual arm of a below-elbow or an above-elbow amputee. The device is expandable in length or size to accommodate child growth and it includes grasp locking and individual finger locking capability. It provides a wrist joint having three degrees of freedom, dynamic tensional rotation control of wrist, dynamic grasp control to allow grasping of irregular objects, extended grasp for gripping larger objects, excessive force breakaway, and algorithms that facilitate use and adjustment of the prosthesis by the user or care-provider.
U.S. patent application No. 022429, entitled Prosthetic Hand Having A Conformable, Compliant, Grip And Opposable, Functional Thumb, filed Oct. 5, 2006 by Winfrey discloses an anthropomorphic artificial hand having a mechanical system that allows the digits to be compliant to pressure that tends to flex the digits and provides for the digits to be self-biasing to conform to the shape of the object being grasped. The hand includes one to four fingers, with the fingers having up to three joints each. The hand may also include a thumb that can be rotated into and out of the opposition to the fingers. The joints of the thumbs are also self-biasing to allow conformance to the object being grasped. This allows the hand to use two cables to operate if body powered (one for the fingers, one for the thumb). The hand may also be electronically powered using two channels for operating the fingers and thumb simultaneously.
U.S. Pat. No. 6,423,099, entitled Safety Clutch For A Prosthetic Grip, filed Jul. 23, 2002 by Iversen, discloses a grip for an artificial or prosthetic arm. The novel structure includes at least two opposable digits and a drive linkage powered by a drive motor. When the drive motor is powered it enables the two opposable digits to grip. The drive linkage includes a drive and transmissions attached to the drive motor. A blacklock is connected to the drive and transmission. Surrounding the black-lock is a blacklock housing containing a drive, selected transmission elements, and the blacklock. A stop element is also included for holding the blacklock housing fixed with respect to ground. The stop element can be released to allow the blacklock housing to move freely and to avoid power transmission without disrupting the operating structure of the transmission.
U.S. patent application No. 0117034, entitled Externally-Powered Hand Prosthesis, filed Jun. 17, 2004 by Weir et al., discloses an externally-powered prosthesis mechanism usable with persons with amputations at or proximal to the level of the metacarpophalangeal joint, as well as persons with high-level amputations. The prosthesis mechanism includes a grasping mechanism including a mechanically operable thumb member kinematically linked to the finger member such that the grasping mechanism is disposed in respective opened and closed configurations when the finger member is respectively moved away from and toward the thumb member. The prosthesis mechanism further includes a drive system extending tangentially with respect to the grasping mechanism and includes a motor operatively connected to drive at least one planetary gear stage, which is operatively connected to drive the grasping mechanism to the opened configuration when the motor is driven in a first direction and further drive the grasping mechanism to the closed configuration when the motor is driven in a second opposite direction.
A paper entitled Biomechatronic Design and Control of an Anthropomorphic Artificial Hand For Prosthetics And Robotics Application, published in a journal entitled: IEEE RAS & EMBS International Conference on Biomedical Robotics and Biomechatronics, in February 2006 by Zollo et al., discloses a biomechatronic approach to the design of an anthropomorphic artificial hand. The hand is conceived to be applied to prosthetics and biomedical robotics; hence, anthropomorphism is a fundamental requirement to be addressed both in the physical aspect and in the functional behavior. Regarding the hand mechanics, a cable-driven underactuation is provided to lighten the structure, allow anthropomorphic self-adaptation to the object to be grasped, and simplify the control. Two simple PD control systems are formulated and evaluated in a common task of grasping a cylindrical object. The reference input for the control is derived from data on human subjects performing the same task and extracted by the literature. The paper reports simulation results about the comparison with the human case when both control systems are used to close the fingers, so to derive specific indications for the improvement of the hand design.
A paper entitled “Five Finger Underactuated Prosthetics Hand System,” published June 2006 in the IEEE International Conference on Mechatronics and Automation, discloses a five-fingered underactuated prosthetic hand controlled by surface EMG (electromyographic) signals. The prosthetic hand is designed with simplicity, lightweight and dexterity on the requirement of anthropomorphic hands. Underactuated self-adaptive theory is adopted to decrease the number of motors and weight. The fingers of the hand with multi phalanges have the same size as an adult hand. The prosthetic hand control part is based on an EMG motion pattern classifier which combines VLR (variable learning rate) based neural network with wavelet transform and sample entropy. This motion pattern classifier can successfully identify the flexion and extension of the thumb, the index finger and the middle finger, by measuring the EMG signals through three electrodes mounted on the flexor digitorum profundus, flexor pollicis longus and extensor digitorum. Furthermore, via continuously controlling single finger's motion, the five-fingered underactuated prosthetic hand can achieve more prehensile postures such as power grasp. The experimental results show that the system has a great application value.
A paper entitled: “Design of an Artificial Muscle Actuated Finger Towards Biomimetic Prosthetic Hand” was published July 2005 in the 12th International IEEE International Conference on Advance Robotics. This paper discloses the design and modeling of a prosthetic finger for children. Conventional prosthetic hands are simple grippers that restore only the very basic grasping capabilities of the human hand. This paper proposes a biomimetic approach to prosthetic hand design. The musculoskeletal characteristics of the human hand are studied to extract elements that are essential in the design of a biomechanically accurate hand. A four (4) DOF finger design closely mimics the size and kinematics of the human finger. SMA-driven tendon wires are directly attached to the finger structure, in a manner similar to the natural tendons and muscles.
A paper entitled: “A hydraulically driven multifunctional prosthetic hand” was published May 2005 in Robotica (UK), Volume 23, Issue 3. A new prosthetic hand is presented that closely approximate the grasping abilities of a human hand. A large variety of different objects can be grasped reliably and the movements of the hand appear to be natural. This five-finger hand has 15 degrees of freedom driven by small sized flexible fluidic actuators. The drives are within the fingers allowing a very compact and lightweight hand.
Another paper, entitled “Mechanism Design of a New Multifingered Robotic Hand” was published April 1996 in the IEEE International Conference on Robotics Automation. It discloses a new-finger robot hand (NTU hand) with seventeen degrees of freedom (DOF). In contrast to traditional tendon-driven robots, the NTU hand has an uncoupled configuration so that each finger and joint is individually driven. All actuators, mechanical parts and sensors are packed on the human hand. Such compact design makes the hand easily adapt to industrial robot arm and prosthetic applications.
A paper entitled: “Pinching Finger Tips in Humanoid Robot Hand” was published June 2005 in the 2005 IEEE International Symposium on Computation Intelligence in Robotics and Automation. A small-sized and light-weight robotic hand is designed according to the concept of extracting required minimum motor functions and implementing them to the robot. A robot hand is capable of properly realizing a pinching motion with finger tips, by adding the minimum required degree of supplementary freedom which can be realized only with a machine.
In view of the art considered as a whole at the time the present invention was made, it was not obvious to those of ordinary skill in this art how the art could be further advanced.